6. GOODWILL AND INTANGIBLE ASSETS

A summary of changes in goodwill at June 30, 2018, is as follows:

	Hydraulics			Electronics		Total
Balance at December 30, 2017	$	2,496		$	106,373	$	108,869
Acquisition		248,913			—		248,913
Currency translation		(11,785	)		—		(11,785	)
Balance at June 30, 2018	$	239,624		$	106,373	$	345,997

Goodwill is tested for impairment annually, in the third and fourth quarters, or more frequently if events or changes in circumstances indicate that goodwill might be impaired. Valuation models reflecting the expected future cash flow projections are used to value reporting units.

At June 30, 2018, and December 30, 2017, intangible assets consisted of the following:

	June 30, 2018							December 30, 2017
	Gross carrying amount		Accumulated amortization			Net carrying amount		Gross carrying amount		Accumulated amortization			Net carrying amount
Definite-lived intangibles:
Trade name and brands	$	55,285	$	(3,213	)	$	52,072	$	30,774	$	(2,115	)	$	28,659
Non-compete agreements		950		(301	)		649		950		(206	)		744
Technology		31,217		(3,890	)		27,327		18,435		(2,671	)		15,764
Supply agreement		21,000		(3,325	)		17,675		21,000		(2,275	)		18,725
Sales order backlog		5,840		(3,553	)		2,287		—		—			—
Customer relationships		231,313		(5,377	)		225,936		39,751		(2,607	)		37,144
Licensing agreement		3,716		(741	)		2,975		3,716		(621	)		3,095
	$	349,321	$	(20,400	)	$	328,921	$	114,626	$	(10,495	)	$	104,131

Amortization expense of intangible assets for the six months ended June 30, 2018, and July 1, 2017, was $10,124 and $4,348, respectively. The remaining amortization for 2018 is approximately $11,334. Total estimated amortization expense of intangible assets for the years 2019 through 2023 is presented below.

Year:
2019	$	17,913
2020		17,880
2021		17,779
2022		17,516
2023		17,457
Total	$	88,545